DE3228387A1 - Method of screening halftone image motifs - Google Patents

Abstract

A method of screening halftone image motifs, in which method the picture halftones of the halftone image motif are reproduced by changing the intensity of the structure of a basic screen structure of any form. The allocation of the picture halftone area of the halftone image motif to the intensity of the screen structure reflecting this picture halftone area can be specified in a targeted manner. In a phototechnical version of the inventive method (Figure 1), any desired basic screen structure (1) is made and expanded screen structures are made from it as negative films (9, 11). From the image motif (13) to be screened, the same number of tone value extracts (20, 22) is produced as negative films, each of which reproduces a particular picture halftone area of the halftone image motif which can be adjusted by the exposure time. The tone value extracts (22, 20) are exposed with the expanded screen structures (9, 11), assigned to them in each case, of the row onto a strip material (24) which then reproduces the screened image motif in such a way that the picture halftone proportions defined by the tone value extract are reproduced locally by the intensity of the screen structure assigned thereto. Of this method there are several phototechnical and EDP-scanner-laser variants which are suitable for screening halftone image motifs, for producing screened printing copies and for printing on recording media with image motifs screened in this manner. <IMAGE>

Description

PROCEDURE FOR SCALING BY HIx HAbBTöNB 1 LDMOT IVEN

The invention relates to a method for producing rasterized Motifs in which the gray values of a halftone picture motif are changed by changing a Basic grid structure can be reproduced.

Especially in the production of securities, security prints, Identification cards and the like is the use of security line patterns such as z. B. Guilloches, known for a long time, to imitations or falsifications of such To prevent recording media. Image and safety line pattern to be protected are used as separate elements. In CH-PS 477 066, for example an identity card described in which an in The photo of the cardholder provided on the ID card is secured against manipulation will.

The production of security prints by this method is relative easy and cheap to implement, as the safety pattern does not require any additional measures is printed over the image motif over a large area. However, it turns out to be disadvantageous that in the areas in which the image motif and safety lines are printed on top of each other color mixes arise that disrupt the color continuity of the line.

In the case of a monochrome design of the image motif and line pattern as well as for Very dark motifs are either the safety lines in the area of the motif not at all or only very difficult to recognize. Such security techniques are therefore only used for high quality security prints.

One of the main drawbacks is when printing banknotes Usually, image motifs in recesses or windows of the guilloche background print to use. The image motifs are usually in high-quality steel gravure executed, which in spite of the lack of the guilloche pattern in the picture motif has a high Offers counterfeit protection. However, it is disadvantageous that the area of the Image motif reduces the area that can be used for the background print and that as a result the protection against forgery and falsification made possible by guilloche pattern is reduced very significantly in the case of larger image motifs. Compliance of existing security guidelines (exchange guidelines) in which, among other things a percentage of the minimum surface area is required for the guilloche background, allows the use of full-surface image motifs for those bound by these guidelines Value prints not too.

By circumventing some of the disadvantages of the former method, at which the picture motif is overprinted with the security pattern, was used for the production Another known method of identity cards is to use the photographs themselves in black areas of the photo can be protected by clearly recognizable guilloche lines (see DE-AS 29 07 dz9).

In order to make the security pattern easier to recognize, it was suggested that to provide the photo area with a security pattern before exposure, so that after exposure, the exposed areas of the image motif by an unexposed Security pattern interrupted and thus the lines of the guilloche pattern unchanged are easily recognizable.

Despite the clear advantages of this procedure, it turns out to be disadvantageous that this technique is only applied in connection with photographically Motifs is possible. Use of the advantages of other recording media without photo-technical measures is not possible.

According to a novel method, it has already been proposed to use safety line patterns to be integrated into image motifs on securities or recording media.

The imprinted image motif is replaced by another that is also imprinted Line pattern superimposed, the image motif adapted to the line pattern by a Negative contour is interrupted and the line pattern is imprinted congruently. Depending on Embodiment, the lines of the negative contour can be just as wide as the lines of the line pattern or wider, so that the safety lines each have a small distance to the picture motif on both sides and thus the picture motif run through as free lines without touching.

This process is characterized by the fact that it is used in the manufacture the recording medium manages without photographic techniques and in particular for the production of value prints opens up new possibilities, since now even the simplest Image motifs completely independent of the image size, i. H. so also over a large or full area, In terms of security, it is of high quality and designed in accordance with stock exchange guidelines can be. If the printing techniques customary in security printing are used the safety lines and negative contours run very finely, so that one with Exploitation of the technical color possibilities Securities receive, their imitation or eprution very difficult or with simple auxiliary means During the above-mentioned process for the production of recording media is not necessary Ultimately, use the image motif and safety line pattern as separate elements, methods are also known in which the image information is through in the line width varying safety lines is generated. These procedures are based on the Printing and repro technology known use of glass engraving or distance and contact grids for rasterization of image information. There are various types of trade and customary use Raster shapes, such as B. point, cross, lines or grain grids, which are characteristic for the grid forms is that they consist of simple, regular geometric structures (Dot, cross, line grids) or from statistically evenly distributed irregular ones Structures (grain grids) exist. The variation of such grid shapes is through the manufacturing possibilities are limited.

Starting point for the production of the contact grids that are widely used today are the distance or glass engraving grids.

The production of glass engraving grids is complex and cost-intensive, what the manufacturing process makes clear. The starting point are two absolutely plane-parallel Glass plates that are coated with a hydrofluoric acid-resistant layer and then inserted with the diamond scraper of a line machine the line width in the etch-resistant layer is scratched. After the lines have been deeply etched with hydrofluoric acid, the The hydrofluoric acid-resistant layer was removed and the deepened Lines become colored with black paint. The cross line effect # of the grid then arises in that the two line grid plates are engraving on engraving at an angle of 900 are cemented together.

Because slightly a deviation from the intended one due to the etching of the lines Line relationship can occur, the work results are with different grids same grid width sometimes quite different, in particular can the line width in the production of line grids only within certain limits Control tolerances. Furthermore, due to the manufacturing method, it can also be seen that no complicated grid structures such. B. multiple crossing and intertwined lines or other complicated irregular grid structures, can be produced. Only essentially parallel, one-way running, sets of lines that do not cross on a glass plate.

Contact grids are produced based on a glass engraved grid, by placing fine-grained halftone emulsions a certain distance behind you Glass engraved grid exposed and then developed.

An unlimited number of pieces can be produced from a glass engraving grid of contact grids produce, whereby the by the expensive and complex manufacturing process of the glass engraving grid are significantly reduced for the user can. For the possible grid structures in contact grids produced in this way The same restrictions apply because of the glass engraving grid used as the initial grid and limits as for the glass engraving grids.

The rasterization of a sub-tone picture motif with a contact raster, which has a continuous gradation, is done by a line material with an almost digital gradient through the negative or positive of the halftone motif and the contact screen exposed, with halftone negative or positive and the contact grid are in direct contact with the coating material. Depending on the exposure, the halftone negative is then formed in the line material as a result of the exposure or -positively transmitted light from the grid structure used, which reproduces the image information by thickening or tapering grid structures.

The same result, but with greater technical effort, can be achieved by rastering the image motif directly with a glass engraving grid.

For this purpose, the line material becomes through the halftone negative or positive the image motif, a suitable aperture to be selected and the glass engraved grid exposed, where the distances between the line material and the grid and between the grid and the aperture must be precisely coordinated.

With both types of raster, you can achieve a smooth reproduction of Semitones.

Another method of making a particular contact grid, which is not based on glass engraving grids and means that the contact grid is a stepped pattern Has gradation has been described in DE-PS 166 722. This is done by a black and white raster consisting of light and dark straight stripes, a photographic reproduction made in the form that during exposure the objective of the camera perpendicular to the line direction on or is shifted several times to such a small extent that the new raster images only by some of the line width against the first appear crazy. It is created like this Stripes of graduated coverage. The grids fabricated in this way deliver as contact grids a gradual reproduction of semitones. However, this method is disadvantageous in addition to the mechanically very complex manufacturing process that only just parallel Let lines be implemented sensibly in step grids.

The use of line grids in the manufacture of securities is already known from DE-PS 368 134. The effect of the image is completely or partially by parallel or almost parallel, produced using a glass engraving grid, straight or crooked lines are produced, which change as the toning of the image increases continuously widen and merge in the darkest areas. from the halftone original converted in this way are made with the usual photomechanical Process printing plates made.

The disadvantage of this process is that it involves production is subject to limits and restrictions associated with glass engraving grids. So can be z. B. only simple grid structures of parallel or nearly parallel Make lines that join and clump together in the darkest areas can. Complicated grid structures, such as intersecting, intertwined Line patterns or, for example, the high-quality guilloches in terms of security or irregular, Structures of any complexity cannot be produced in this way. Also the use of contact grids ru this fact change, as their production is also based on glass engraved grids. The security-related Value when using parallel or nearly parallel lines would be because of the despite all still existing forgery and adulteration possibilities as not special to rate high.

The object of the invention is therefore to provide a method for production to create a rasterized image motif, which is not the one with the production classic contact grid is subject to associated limits.

The solution to this problem is based on the basic idea, not how In the known raster technology, the entire gray value range of the screen to be rasterized Halftone motifs in one step with a classically produced contact screen rasterize - whereby the assignment of the respective, locally available gray value of the Halftone image motif to local structure strength of the grid cannot be influenced and the shape of the grid is subject to the limits of production technology - but rather to divide the gray value range of the halftone image motif to be rasterized into areas, the limits of which can be freely defined, all or selected ones of these gray value areas a certain, but freely definable structure strengthens an arbitrary shape Assign the grid structure and the portions of the halftone image motif, which have a gray value from one of these areas, locally in those assigned to this gray value area Implement grid structure strength.

In a further development of the invention, the gray scope of value of the halftone image motif is not divided into areas, but it is each gray value assigned a certain grid structure strength.

Regarding the terminology, it should be noted that the term "gray value" is used as equivalent to the terms commonly used in photo and repro technology such as "gradation", "blackening", "Density" ("gray value" = log (opacity)) is to be viewed and in this context is also used representative of these terms, since the inventive method is not limited to black and white motifs and, by analogy, also to color motifs can be transferred.

The solution to the problem of the invention was achieved by various photo-technical Process achieved, however, also in an engineered variant using a scanner, an EDP system and an EDP-controlled laser can be implemented can. The main features of the invention are first based on the photo-technical Procedure explained.

In the first photo-technical process, in the following ~ single-step tone value process " called, tone value separations are produced from the halftone image motif to be rasterized, each of which reproduces the proportions of the halftone image motif, which gray values a gray value range that can be precisely set using the exposure time on the gray value scale reproduce.

From a basic grid structure, which can have any shape - e.g. B. a complicated line pattern of intersecting and intertwining lines, Sequences of letters, numbers or line replicas of richly structured landscape motifs and not finally classic raster formsw -, are line replicas increasing structural strength, d. H. gradually expanded grid structures, produced, either graphically or by applying a negative film of the basic grid structure on a line material and targeted overexposure, with for each overexposure process a new line material is used and the exposure time corresponds to the desired expansion of the grid structure is increased.

The number of expanded grid structures produced in this way corresponds to the number of previously created tone value extracts of the halftone image motif and thus the number of gray value areas to be converted. The further implementation process of the halftone image motif in a rasterized image motif happens in such a way that a Negative film of the raster structure with the greatest structural strength, d. H. the greatest Expansion compared to the basic grid structure, together with a negative film of the Tone value separation of the halftone image motif with the lowest structure thickness - the tone value separation with the lowest structure strength shows the proportions of the halftone image motif, which have the darkest gray values, the limit of this gray value range was determined by the exposure time when producing the tone value extracts - be placed in Kontaktanordnang on an unexposed line material, this Arrangement is exposed until in the areas of the. Line material where the arrangement of negative film of the grid structure is greatest. Structure strength and negative film of the tonal value separation of the smallest structure thickness is completely translucent, a complete blackening has taken place, so that the one determined by the tone value separation Gray value range of the halftone image motif, d. H. here the darkest gray values in which exposed Line material is reproduced by the grid with the greatest structural strength.

With the following grid structures of decreasing structure thickness and the tone value extracts of increasing structural strength and each with a new line material is proceeded in the same way.

The result is a completely screened halftone image motif, whereby the different gray values of the halftone image motif in rasterized form present on the various line materials. These line materials can either copied together for complete image information and for the production of a Printing plate can be used, or any line material is used for the production a separate printing plate is used, so that each gray value area of the halftone image motif can be printed separately in rasterized form. Of course it is also possible Copying only certain line materials together to make a printing plate and use the remaining line materials to make separate printing plates. If a security line pattern made of guilloches is used as the basic grid structure, it is particularly useful to add this basic grid structure to one of these Line materials or to be copied into the completely screened halftone image motif or to produce a separate printing plate from this, so that in the rasterized or printed motif, the line course of the guilloché pattern in all parts of the picture is visible and traceable without interruption.

Special effects can be achieved by using the different Printing plates present screened gray value areas of the halftone image motif prints in different colors, so that different gray value areas don't just go through different grid strengths, but also represented by different colors will. The cross section through such a printed raster line then has a step-pyramid-like gradient consisting of different layers of paint, where the number of steps is proportional to the width of the grid line and thus to the Is the gray value of the halftone image motif in this area. The use of metallic, metameric, thermo- or photochromic colors offer completely new ones with this process Possibilities for increasing the security against forgery or forgery of Securities or banknotes.

Another advantage of this process is that it can be used by any any structure can be used as a basic grid structure, so that the earlier, with the production of classic grids such as dot, line, cross or grain grids boundaries become meaningless. As a basic grid structure, for. B. use: parallel, almost parallel, spiral, star-shaped, intersecting or intertwining systems of lines with zigzag, wavy, arcuate, circular ones or straight course; Guilloches, e.g. B. also centric guilloches; Words, numbers, Characters; geometric structures such as circles, ellipses, triangles, other polygons; classic grid structures such as dot, line, cross or grain grids; Structural elements a second motif, e.g. B. the line reproduction of a richly structured landscape motif; a rasterized image motif.

It is also advantageous that the implementation Gray value the halftone original can be controlled in a specific grid structure thickness, both in terms of the number and extent of the gray value areas to be implemented, as well as the raster structure strength assigned to each gray value area. Depending on the number of in Position and extent on the gray value scale freely definable gray value areas to be implemented of the halftone image motif, a gradual to continuous gray value reproduction can be achieved through a stepped to continuous expansion of the basic grid structure achieve.

In this context, it is also a good idea to take advantage of the To make use of magnification technology.

If it is z. B. is about the reproduction of extremely fine motifs or very fine grid structures are used as the basic grid structure, it is advantageous to all process steps to achieve a very differentiated gray value reproduction to be carried out with enlarged negatives or positives and only at the end the rasterized one Reduce the print template to the desired size. Should z. B. about the gray value curve of the template are reproduced in 50 levels, the basic grid structure, which can consist of very fine guilloches or other fine structures, 50 gradually expanded grid structures produced on an enlarged scale.

If you enlarge the image motif to be rasterized or the tone value extracts (in this case also 50) accordingly and then carries out all procedural steps with these enlarged structures, so that inaccuracies in the Repeat that occur with such a large number of stages when working in normal size can be traced back to pass problems or with the finite grain size of the photographic material and statistical fluctuations at the edge zones of the structures related, bypassed or on a Minimum n: ate reduced. Even The advantage of creating the grid structures is not overlooked to leave, since coarser structures can be produced with less effort and at the end Better to reduce the size than very fine structures that are the same in original size to be produced.

When working with very few steps, e.g. B. three, on the other hand it is to improve the optical quality of the artwork, all process steps are favorable to be carried out with greatly reduced grid structures.

The finite grain size of the photographic material is used and not quite step-shaped gradation of the line material in order to avoid the otherwise to weaken the sharp jump between two shades of gray in the rasterized artwork and to make it more continuous. If you work in all procedural steps on a greatly reduced scale and only then enlarges the rasterized print template to the desired size, you get almost due to the effect just mentioned continuous transitions between the different; the different gray values of the halftone image motif to be rasterized.

A slightly different process to improve the optical quality the print template, which is suitable for every number of levels and in addition to the even can be applied, consists in the copied together Rasterized image motif, but still without the additional basic raster structure, reproduce in a repro camera with a certain degree of blurring on line material.

The blurring is adjusted so that the step-shaped Transitions in the rasterized image motif are weakened and made more continuous will.

In this unsharp reproduced rasterized image motif is then copied the sharply drawn basic grid structure.

Another phototechnical version of the inventive method, the so-called "single-step halftone process" in the following bypasses the production of tone value extracts from the halftone image motif to be rasterized and used instead one of which is a negative of the halftone image motif. The procedural steps in this procedure run completely analogously to the "single-step semitone method", only that in this one Case in the individual exposure processes tonal value separation - raster structure - line material the different tone value extracts through the halftone negative of the image motif to be rasterized are replaced, with the one to be converted into the respective grid structure thickness The gray value range of the halftone image motif is set by the exposure time.

Another photo-technical version is what is referred to in the following ~ Contact grid halftone process ", in which a contact grid is first produced and then rasterized the halftone image as in the classic raster technique will. The inventive core of this process lies in the production of the contact grid, because here the production of glass engraving grids and the related manufacturing technology Boundaries are bypassed. In this process, negative films are made gradually expanded raster structures one after the other in contact arrangement on an unexposed one Halftone material laid and exposed for a certain period of time, so that nacil Completion of all exposure processes with the gradually expanded raster structures each grid element of the basic grid structure with one through the individual exposure times defined and precisely adjustable gray value or blackening curve mapped will. For example, if a security line pattern made of guilloches is used as the Basic grid structure, the cross section through a grid element, that is one line, one step-shaped depending on the number of expanded grid structures until continuous gray value or blackening progression. The shape of this blackening curve can be achieved by varying the exposure times and the number of expanded raster structures as well as controlled by the degree of expansion during their production in a targeted and arbitrary manner which is not possible with the classic contact grid production. In this Positive contact grids produced in this way can be halftone positives as in the classic one Grid technology (production of negative contact grids analog by replacing positives with negatives and vice versa).

With this method any structure can be created in a contact grid map, which can be used to rasterize a picture motif. Advantageous with this The method is, in particular, any controllability of the gray value or blackening curve in the contact grid as well as complete freedom in the choice of the basic grid structure. The gray value reproduction during the rasterization of an image motif can be controlled by the control of the blackening progression in the contact grid '<can be set as desired, certain Gray values can be suppressed, shifted or also highlighted (this control the gray value reproduction is of course also possible with the single step method). Another benefit of this procedure is its profitability - quite in contrast to the production of glass engraving grids, which only afterwards Making a large number of contact grids are worthwhile. Also suitable Both processes, the single-step process and the contact grid process, are particularly different for security printing, since the use of original guilloches is required for this but # multiple use of the same guilloche pattern is prohibited.

A major advantage, especially of the single-stage process, lies in the fact that only a single original artwork is created with it, because the production of a contact grid, which enables an identical reproduction is circumvented and the process can only be understood with knowledge of the exact "recipe" (individual exposure times, structural strengths of the line replicas etc.) can be done. At this point it should be noted that with all photo-technical Variants the exposure sequence during the rasterization process is arbitrary and only For the sake of better comprehensibility, a certain order in the presentation was chosen. In addition, working with the positive is also included in all variants Negative film equivalent, so all positive or negative film processes can be carried out. Possible change between positive and negative working methods are not explicitly mentioned, as they are self-evident to the person skilled in the art.

The core of the method according to the invention - above were the photo-technical Variants explained - can, however, also be converted into an "engineered" variant realize, if you make use of EDP, computer graphics, laser and scanner technology.

The main features of such a "technical" variant are briefly outlined in the following, with a distinction between two somewhat different must distinguish between technical processes: a so-called "EDP single-stage process" and an "EDP contact grid method".

There are different options between photo-technical and "technical" variants Jump or changeover options, so that you can use the process at different points can combine. These interfaces are not specifically mentioned in the following, since they are clearly evident from the process flow for the average person skilled in the art.

The most important technical devices for the "technical" processes consist of an IT system and a graphics-capable terminal, one with the IT system connected scanning device and a laser beam recorder controlled by the EDP system.

The first step in the engineered process is production a basic grid structure. This can either be done with the aid of computer graphics or generated via suitable mathematical programs, with the shape and position of the grid elements are saved, or there is a suitable one on graphic or by photo-technical means scanned the original and the shape and position of the grid elements also saved.

The gradually expanded grid structures can either Generated from the Pçaster basic structure using the EDP system, saved separately and displayed optically, or photographically created expanded Scanned raster structures and also saved separately.

The EDP-technically generated expanded grid structures can also implemented on a line material via a computer-controlled laser beam writer by the laser with the information about the location and shape of the grid elements the relevant raster structure exposed a line material in a controlled manner.

In the case of the "EDP single-stage process", the halftone image motif to be rasterized Electronic tone value extracts are created in which the entire gray value range of the halftone original is divided into freely definable gray value areas according to location and scope and the halftone original is scanned separately for each gray value area in such a way that the proportions of the halftone image motif which have a gray value from the relevant gray value range have to be stored according to position and shape. Arranges by means of the EDP system if an expanded raster structure is assigned to each gray value area, the stored ones are superimposed Information about the proportions of the halftone image motif from the relevant gray value range and the information about the assigned raster structure in which this gray value area is to be implemented in such a way that for each point, at the grid structure and image motif portion is present, resulting information is stored. This resulting Information is provided by the proportions of the image motif that have been converted into the relevant grid structure from the selected Gray value range again and can optically displayed on the screen or on a line material via the computer-controlled laser be transmitted. This procedure is used for each gauze range and for each of these assigned grid structure carried out in the same way. The in these "electronic" Rasterization processes, stored separately for each gray value area, resulting information can also be superimposed, stored and optically based on the screen, so that one can get an idea of the overall picture rasterized image motif receives. Via the laser controlled with this information the completely rasterized image motif can also be applied to a single line material be transmitted. Of course it is also possible with the help of the computer-controlled Lasers the rasterized image motif directly either on a printing plate or the to transfer individually screened gray value areas onto different printing plates.

In the case of the "EDP contact grid method", what is known as an "electronic one" is used first Contact grid "generated.

This happens e.g. B. in that each of the, as described above produced, expanded raster structures is assigned a gray value, this Gray value information of the information about the position and shape of the raster elements of the relevant Grid structure is added, all information about the expanded grid structures with the assigned gray values are superimposed in such a way that a result # r # nde Information is formed which gives each point of the grid structure a certain gray value assigns.

This gives you an "electronic contact grid, which has a by the shape of the basic grid structure, by the number of expanded grid structures and precisely adjustable gray value curve defined by the gray values assigned to them having.

Another variant when generating an "electronic contact grid" consists in creating a basic grid structure as described above and for a characteristic raster element, a gray value curve using the computer graphics to be defined by e.g. B. the gray value as a function of the position coordinates (x, y) a characteristic grid element of the basic grid structure is defined and optically is pictured. if this information is transferred to the entire basic structure, this also gives an "electronic contact grid".

With this information a laser can be controlled again the raster structure and the defined gray value gradient on an unexposed halftone material exposed. This contact grid, which is available as a halftone material, can then be used as in the classic raster technique can be used.

There is also a direct rasterization of a halftone image motif possible, whereby the production of a photographic contact grid is bypassed. Is z. B. scanned the halftone original to be rasterized so that for each point of the halftone image motif, the C <auwert present there is stored and superimposed this information with the stored "electronic contact grid" in such a way, that for each point of the halftone template and the electronic contact grid the Gray values are added, whereby the resulting information is saved, if a certain, empirically determined gray value threshold is exceeded in the case of this addition, the resulting information is obtained from this a completely rasterized image motif, which is displayed optically and by means of a laser beam writer on a line material or directly on a printing plate can be transferred.

Concerning the "engineered" processes, it can be said in conclusion that they Due to the use of a graphics-capable EDP system and a scanner # extremely are variable in the generation of raster structures and gray value gradients, one Immediate implementation of a halftone image motif in any grid structure and the visual representation of this rasterization on the screen enable what when trying out new grid shapes, the value should not be underestimated because Among other things, the time required compared to the classic method is considerable reduced. In the following, with reference to the Fig.

the invention explained in more detail.

Fig. 1 a schematic representation of the process sequence in the ~ single-step tone value process " Fig. 2 Basic grid structure positive (schematic) Fig. 3 Basic grid structure negative (schematic) FIG. 4a first expanded grid structure positive FIG. 4b second expanded Raster structure positive Fig. 5a first expanded raster structure negative Fig. 5b second expanded raster structure negative. FIG. 6 halftone image motif to be rasterized Fig. 7a first tone value separation negative Fig. 7b second tone value separation negative Fig. 8a first positive raster result FIG. 8b positive second raster result FIG. 9 rasterized Image motif Fig. 10 Grid structure strength as a function of the gray value of the halftone original Fig. 11 Exposure arrangement “single-step halftone process Image motif Fig. 13 Expanded raster structure positive Fig. 14 Tone value extracts Fig. 15 raster results, individual steps Fig. 16 rasterized image motif Fig. 17 basic raster structure guilloches Fig. 18 rasterized image motif Fig. 19 characteristic line intersection guilloches Fig 20 ~ Contact screen halftone process "Fig. 21 Exposure arrangement during contact screen production Fig. 22 Gray value progression in the step contact raster. Fig. 23 Stepped approximation of a continuous gray value curve in the contact raster Fig. 24 Gray value curve in the contact grid after unsharp exposure Fig. 1 shows a schematic flow chart of the "single-step tone value process" or "EDP single-step process", where the individual steps are explained in more detail with reference to the following FIGS. 2 to 9.

For a better understanding of this method, FIGS. 2 to 9 Worked with highly schematic representations and only those for understanding are used essential steps are shown. Further below, with reference to FIGS. 12 to 18, the Procedure with more realistic grid structures briefly presented again; around to give a small impression of the possible applications.

It should also be noted that the photo-technical version of the process always comes first explained and then briefly outlined the "engineered" variant, which from The process sequence is essentially analogous to the photo-technical version. Possible Interfaces, d. H. Possibilities to switch from the photo-technical to the "technical" Variants, are usually only briefly indicated or not explicitly mentioned because these interfaces in principle between all procedural stepped can lie and are therefore obvious.

The left branch of the process flow chart in FIG. 1 shows the generation of expanded raster structures from a basic raster structure or original raster structure. From a positive 1 of the basic grid structure - FIG. 2 shows a positive 1 of such a structure highly schematized basic grid structure defined by seven strips 2 of a Structural strength is symbolized, with the strip 2 is completely opaque - is a negative film 3 (Fig. 3) was prepared.

From this negative 3, expanded raster structures 5, 7 are used as Line replicas are made (in this case two) by placing the negative 3 on one unexposed line material is placed and through targeted control of the exposure, d. H. targeted overexposure, a widening of the stripes is achieved.

4a shows the positive produced during the first exposure process 5 with widening stripes 6, d. H. with an opposite of the basic grid structure increased structural strength.

4b shows the positive resulting from the second exposure process 7 with even more widened stripes 8. The degree of widening is determined by the Exposure time can be controlled in a targeted manner.

The next step in Fig. 1 consists of these as positive film 5, 7 existing line replicas of increasing structural strength negatives 9, 11, which are shown in Figs. 5a and 5b.

The right branch in Fig. 1 shows the preparation of the rasterized new Halftone motifs 1 3.

In Fig. 6 a positive 13 of the image motif to be rasterized is shown, a circular ring with two different gray levels 14 and 15, representing any continuous gray value course of the halftone image motif to be rasterized.

This positive 13 of the halftone image motif (FIG. 1) becomes a negative film 17 produced, from which tone value extracts then present as positive film 18, 19 are created by placing the halftone negative 17 on a new unexposed one for each tone value separation Line material is laid and exposed for a certain period of time.

The duration of the exposure depends on the gray value the halftone image is to be "pulled out". In this example, for the first The exposure time selected so that the black circular ring 15 is off Fig. 6 is "pulled out", that is, the tonal value separation with the lowest structure strength just reproduces the darkest area of the halftone image motif.

All gray values of the image motif, starting with white up to a certain, Gray values that are suitable to be selected are integrated on the whole to white and the remaining ones Gray values to black, with the transition here (with the first tone value separation) chosen in this way became that it lies exactly between the gray values of the circular rings 15 and 14 (Fig. 6).

For the second tonal value separation, the exposure time is increased so that that in addition to the circular ring 15 (Fig. 1) also the next gray value area, the circular rings14, be pulled out, so overall a bigger one Gray value range of the halftone image motif reproduced by this second tone value extract will.

From these tone value excerpts available as positive film 18, 19 (Fig. 1) negative films 20, 22 (Fig.1) shown in Figs. 7a and 7b are produced are.

Fig. 7a shows the negative of the first tone value separation with the narrowest Structural strength, d. H. the darkest "drawn out" area in the halftone motif, here the ring 21, which corresponds to the ring 15 in FIG.

Fig. 7b shows the negative 22 of the second tone value separation larger or increasing structural strength 23, d. H. the larger one determined by the exposure time, The solid gray value range, which in this case consists of the rings 14, 15 from Fig. 6 consists.

With the previous procedural steps it is already determined which Gray values or gray value areas of the halftone image motif in which expanded structure strength the basic grid structure should be implemented. The actual implementation process is at the bottom of FIG. 1 when the left and right branches of the method are combined shown. The line reproduction 9 available as negative film with the narrowest structure strength is combined with the tonal value separation 22 present as a negative film with the greatest structural strength in contact arrangement on an unexposed line material 24 laid. This arrangement is exposed until in the areas of the line material where the arrangement is completely translucent, a complete blackening takes place is, so that determined by the tone value separation 22 Gray value range of the halftone image motif (the ring 23 in Fig. 7b) through the grid with the narrowest Structure strength is reproduced.

The result of this exposure process is shown in FIG. 8a. The positive 27 shown there of the above exposed line material 24 gives the expanded Raster structure 28 again in the areas where the tone value separation 22 completely absorbs the light lets through, d. H. in the area of the ring 23 in FIG. 7b.

With the second tonal value separation 20 (Fig. 7a) with the lower structural strength and the line replica 11 (Fig. 5b) associated therewith of lesser structural strength and A new, unexposed line material is processed in the same way.

The result of this second exposure process is shown in FIG. 8b. The two exposed and developed line materials can then be used full screened image information can be copied together.

Fig. 9 shows the completely rasterized image motif as positive 33, with the basic grid structure or original grid structure 2 (from Fig 2) was copied. The darkest gray value range from the halftone image to be rasterized 13 from Fig. 6 is reproduced locally by the most expanded grid structure 34, the lighter areas due to the grid structure with the lower structure thickness 32.

Copying in the basic grid structure 2 is particularly advantageous when using guilloches as the basic grid structure, as this is the course of the lines is continuously traceable in all parts of the picture, what about security printing is considered an important security feature.

The rasterized portions (Fig. 8a and 8b) of the motif can for the production of printing plates 25 (Fig. 1) are used, either for a separate printing plate is created for each part (Fig. 8a or 8b) (e.g. by means of the known contact copying process), so that the individually rasterized Gray value areas of the halftone image motif are present on different printing plates and are printed separately (the basic grid structure may be in one of the parts beforehand copied in or a second, additional printing plate created for this), or es the overall rasterized image motif from FIG. 9 is applied to a single printing plate transferred and with known methods customary in security printing technology such as Simultaneous jerk etc.

overall printed. In addition, known from security printing technology, Optical effects achievable via color gradient techniques and the like are used as well as colors that cannot be separated or only with great difficulty in terms of reproduction are.

One works with several printing plates, which the different gray value areas can be used to reproduce special colors, but also in terms of security Achieve interesting effects if the individual printing plates have different colors wear, which are passergenåt printed on top of each other, so that in the finished printed Recording medium 26 (FIG. 1), depending on the structural strength of the grid structure, is a step pyramid-like one Line cross-section results, which consists of different layers of paint. The usage metallic, metameric, thermal or photographic chromer colors for one or more of these color layers form a particularly valuable security feature, because this is specifically introduced into the image structure and, so to speak, a part represents the image information.

The printing options mentioned here also apply to all the procedures outlined below, and it is therefore no longer special responded to them.

The implementation of the continuous gray value curve is shown on the basis of FIG a halftone original in a stepwise expanded grid structure. The diagram is to be interpreted in such a way that the one plotted on the G axis continuous gray scale in certain structure thicknesses B of the raster structure is implemented, d. H. the diagram shows the structure thickness B as a function of the gray value G of the halftone original. All gray values from 0 to the value a are determined by the copied in original grid structure width d reproduced, the values from a to b by the width e and the values from b to c by the width f. Assuming one Halftone negative of the image motif with a continuous gray value gradient, so can z. B. at point a small statistical fluctuations in the incidence of light to irregular, lead to uncontrollable fluctuations between the two grid widths e and d, which affect the quality of the optical impression of the screened image motif can. With the tone value extracts you are now able to set the limits, up to those the gray values of the original to be integrated to black, so that you are exactly below the jump area from grid width d to e and these Fluctuations become irrelevant.

Of course, with these methods it is also possible to use any To select the setting of the limits and thus the gray value reproduction through a certain Exact control of the structural strength or expansion of the basic grid structure. One can also with any number that can be produced within the scope of the technical possibilities Grid levels work and a quasi-continuous to continuous course reach. The particular advantage of this process is that you can choose freely has independent parameters, which are exactly and at all times during each process step can be coordinated in a controllable manner.

Before going to the "EDP single-step method" corresponding to the "single-step tone value method" will be discussed in more detail, first there are further photo-technical variants of the single-step process briefly presented. Instead of doing the exposures with the pairs as explained above: Line reproduction of the raster - assigned tonal value extract on a new line material each time 24, it is also possible to carry out all exposure processes on the same Line material 24 perform so that the copying together of the individual rasterized Shares is bypassed.

In addition, the sequence of the exposure processes is arbitrary, which applies to all photo-technical processes.

Another phototechnical variant is the "single-step halftone process", which is basically the same as the "single-step tone value process". Deviating of this, however, no tone value extracts are created from the image to be rasterized, but it is used instead of the tone value separations 18, 19 or 20, 22 (Fig. 1) worked with the negative film 17 of the halftone image motif. The one from this Halftone image motif to be converted into the gray-scale value area assigned to it in each case is used during the exposure process with the gradually expanded raster structures 9, 11 determined by the exposure time.

Dark gray values of the halftone positive to be screened are highlighted short, light gray values due to longer exposure times in the area assigned to each area, expanded grid structure implemented. In the above example, the line copy is used 9 (Fig. 5a) of the lowest structure thickness together with the halftone negative 17 of the Image motifs to be rasterized in contact arrangement on an unexposed line material 24 and exposed until the dark gray values of the halftone positive are reproduced by the grid structure thickness of the line reproduction 9, with the exposure time the limit of this gray value range can be specifically determined can. With the following line replica 11 (Fig. 5b) of increasing structural strength and the same Halftone negative 17 is proceeded in the same way, except that the exposure time is correspondingly the gray value range to be converted is enlarged.

Fig. 11 shows the schematic exposure arrangement in the ~ 1 single-step halftone process ", in the example shown here, all exposure processes on a single one Line material are made and the exposure times are chosen slightly different in this case must be than in the "single-step halftone method", in which expanded for each Grid structure a new line material is used. The halftone negative 17 of the rasterized image motifs with their different, the image information again- giving Gray values in the photo emulsion layer 43, is in contact with a negative film 11 present line replica of the expanded basic grid structure in the area of the grid structure 12 is completely transparent to a coating material 24 placed and exposed to parallel light 44 for a precisely defined period of time. This exposure process of the line material is carried out with every expanded raster structure repeated. In the area of the grid window 12, the line material is depending on the incidence of light blackened. In this case z. B. the exposure process widened with the second Grid structure shown in Fig. 5b. So much light is falling through in area 39 the grid window 12 to effect complete blackening while in the area 40 the amount of light is just enough, due to the cumulative effect of incident light in the photosensitive layer of the coating material already in the first exposure process exposed with the narrowest grid structure thickness, but not completely there blackened area that almost exceed the digital gradation threshold of the line material to leave and cause a blackening.

The blackening extends beyond that left free by both grids Area, d. H. so here only over the grid width of the narrowest grid; the from The area left free in the second grid is not yet blackened here, because the total amount of light has not yet been sufficient. Would you still be able to widened grid structures work, so this exposure process would with carried out analogously to each expanded raster structure, with the respective exposure times can be precisely adjusted to the desired halftone conversion of the image motif in narrower or wider grid structures to achieve.

The production of printing plates and the printing of the recording medium runs analogously to the "single-step tone value method". For the "IT single-step process" In principle, the same process sequence applies as shown in FIG. 1. Of the better Understanding and highlighting the possible interfaces between phototechnical and "engineered" procedures will be the course of this procedure into sections 1. Generation of the basic grid structure 2. Generation of the expanded Screen structures 3. Generation # of the "tone value separations" 4. Split screen process. Behind each of the sections 1. to 4.

can practically "switch to the photo-technical process" or jump from the photo-technical process to the "technicalized" process.

The technical equipment for the "engineered" processes exist from an IT system with a graphics-capable terminal, one with the IT system connected scanning device and a laser beam recorder controlled by the EDP system.

Section 1: Generating the basic grid structure The basic grid structure can be done by means of computer graphic techniques (~ light pen ", etc.) or by special mathematical programs are generated (e.g. if a grid structure from mathematically representable yjinien structures or other geometric structures how circles, triangles etc. are built).

This grid structure is saved separately, so that the shape and position each grid element are uniquely determined (e.g. by adding each point of the basic grid structure information is assigned that provides information on whether at this point Grid structure is present or not).

At this point there is already a transition to the photo-technical process possible by using the information stored about the shape of the grid structure the laser beam writer is controlled, which puts the basic grid structure on a line material exposed.

The basic grid structure can also be based on photo technology or graphics Path generated, then via the scanning device connected to the EDP system The position and shape of the grid elements are scanned and the information obtained in the process can be saved via the basic grid structure.

2. Generation of the expanded raster structures: The expanded Grid structures can be created from the stored basic grid structure via the EDP system can be generated by an "expansion factor" for each expanded grid structure is defined, the grid elements are expanded by this factor and the shape each expanded grid structure is saved separately (interface to the photo-technical Process by transferring the expanded raster structures onto line material by means of the computer-controlled laser). Of course, it can also be photographed or graphically created expanded Scanned raster structures and their shape information saved separately.

3. "Tone value extracts": The "tone value extracts" are also displayed via the scanning device obtained by defining gray value areas via the EDP the halftone motif is scanned for each of these gray value areas and the Portions of the halftone image motif which have a gray value from one of these areas, are stored separately for each gray value area and to a certain extent in the form of "electronic" Tone value extracts are available (alternative: scanning photographic tone value extracts and separate storage of this information). The advantage of the technical variant with the "electronic tone value extracts" is that problem-free and quick any gray value areas can be defined and extracted.

4. Scanning process The actual scanning process takes place in such a way that a specific, expanded raster structure is assigned, the "electronic tonal value separation", which reproduces the relevant gray value components of the halftone motif, the assigned expanded grid structure is superimposed in such a way that the stored information compared point by point with each other via tonal value separation and assigned raster structure and then, if there is a tonal value component and a halftone component at a point, a resulting information is formed and stored, which states that at this Point is a rasterized portion of the image. This procedure will for each couple: Gray value area - assigned tonal value separation performed and the Information is stored separately for each pair, so that as a result the individual gray value areas reproduced by the assigned raster structure the halftone image motif are stored separately in rasterized form and z. B. can also be displayed optically on the screen.

Next, the individual rasterized, one of the selected Grayscale areas of the halftone image motif reproducing parts over the EDP-controlled Laser on different or a single line material or directly on different ones or a single printing plate can be transferred. It is of course also possible the individual gridded parts in the EDP to the completely gridded image motif to overlay, to visually display the finished rasterized image motif, in addition to superimpose the grid structure and any superimpositions via the computer-controlled laser of the individual, screened parts on one or more printing plates (or also Line materials).

The possibilities of variation are practically unlimited with this method, because due to the speed of the EDP raster structures, gray value areas, expansions, Overlays of rasterized portions changed at almost every point in the process and the results can be viewed directly so that the impact is less Changes of arbitrary parameters on the end result of the rasterization process can observe immediately.

An example that better highlights the design options as the only schematic sketches in FIGS. 2 to 9, is in FIGS. 13 to 16 there- posed. For the sake of clarity, here is with Worked positives, which is of course equivalent to working with negatives.

Fig. 12 shows a shell 45 as a halftone image motif to be rasterized, whereby the following process steps are based on the drawn cut-out window 46 will be explained in more detail.

The text background shown in Fig. 13 (here shown somewhat enlarged), the strip 47 being the basic grid structure and the following strips 48, 49, 50, 51 respectively are gradually expanded by a certain strength.

14 shows four tone value separations (52, 53, 54, 55) of the halftone image motif (Detail window 46 from FIG. 12) with increasing structural strength.

The tone value separation with the greatest structural strength 52 from FIG. 14 becomes in contact with the expanded grid structure 48 of the narrowest structure thickness (Fig. 13) placed on a line material and exposed until the line material completely blackened in the area not covered by the letters or the motif is.

The result of this exposure process is shown as positive 56 in Fig. 15 shown. With the further tone value separations 53, 54, 55 from FIG. 14, namely with decreasing structure thickness, and the grid positives 49, 50, 51 from FIG. 13 with each increasing structural strength and a new line material is then also procedure.

The screened tone value extracts 56, 57, 58, 59 obtained in this way are shown in Fig. 15, with each screened tone value separation the proportions of the Halftone image motifs, which gray values from the, determined by the tone value extract Have gray value area, locally by the assigned tone value separation Represents grid structure strength. These positives are copied together and then In addition, the basic grid structure 47 is copied into FIG.

Fig. 16 shows the image motif obtained in this way, which is used as a print template or can be used for other purposes.

Show another application example of the single step process 17 and 18. The intertwined structure shown in FIG. 17 serves as the basic grid structure Line pattern 61. If you carry out the process steps described above with this grid the screened image motif shown in FIG. 18 is obtained. The image information the shell 62 is here represented by thickening or tapering lines of the grid structure generated, each of which reproduces the corresponding gray value areas of the original.

The line pattern of intertwining lines used in this example and multiple crossing lines (an example of a simple guilloche pattern) brings the special advantages of this process for banknote and security printing only really comes into its own, since in this case the reproduction of image information by thickening or thinning the line structure so that it in the darkest areas and in the narrowest meshes, there is no spillage or together ends of the lines so that the lines of the Guilloche patterns are continuously traceable in all parts of the motif.

In Fig. 19a to c some possible mesh shapes are shown, that of security line patterns with looping and multiple crossings of the Lines can occur.

19a shows a mesh 63 formed by a single line becomes, while FIG. 19b is a mesh 64 formed from two lines and FIG. 19c is a shows mesh 65 formed from four lines. The line width b and mesh width a are coordinated so that the line width b is always less than half the mesh size is a and thus blotches or connecting lines be avoided in any case.

In Fig. 20 is a schematic process flow chart for the photo-technical "Contact screen halftone process" shown, referring to the same schematic Figures (Fig. 1 to 6, Fig. 9) is referenced as in the "single-step halftone method".

The left branch of the flow chart (FIG. 20) shows the manufacturing route of the contact grid. The positive 1 of the basic grid structure (Fig. 1) becomes a negative 3 (Fig. 3) produced. From this, as with the single-step process, through targeted overexposure, line replicas 5, 7 in stages (in this case two Stages) expanded raster structures produced as positive film of the contact grid is done in such a way that the line reproduction 5 with the narrowest structure thickness 6 placed on a suitable, unexposed halftone material and a certain Period of time long exposure. This exposure arrangement is shown again in FIG. The line reproduction 5 (Fig. 4a) with the smallest fixed in the photo emulsion layer 67 Grid structure thickness 6 is in direct contact with a halftone material 68 with its unexposed photo emulsion layer 70 placed and with parallel light 72 a precisely exposed for a defined period of time. The remains during the exposure process Area 69 covered by the grid structure 6 is recessed from the exposure and it only the rest of the area is exposed, which is a certain amount due to the exposure time precisely adjustable gray value or blackening.

Next is the analog exposure process with the second line reproduction 7 (Fig. 20), which has the next higher structural strength 8 (Fig. 4b) and the same, already exposed halftone material 68 (Fig. 21) carried out, with the exact fit Positioning of positive screen 5 and halftone material 68 must be taken into account. Increased the blackening or the gray value in the photo emulsion layer 70 of the halftone material 68 in the second, more expanded grid structure 6 (also Fig. 4b) uncovered area, so that overall with the first exposure a second Gray or blackness level arises.

In FIG. 22 is the stepped gray value or blackening curve a contact grid shown how to get it with three levels. ', d. H. three widened Grid structures (in this illustration, the The basic grid structure from Fig. 2 was used positively). The step width, i.e. H. broad the blackening or gray value levels is in each case determined by the structure thickness, i.e. H. here width, of the evolved expanded grid structure is determined and the step height, d. H. the jump in the gray value or

Blackening progression, through the respective, freely selectable and precise adjustable exposure time.

With a contact grid 73 produced in this way (FIG. 20) is then the halftone image motif 13 to be rasterized (Fig. 20), from which a negative film 17 was created, rasterized in the classic way by using negative film 17 of the image motif and contact grid 73 in contact arrangement on an unexposed line material 24 placed and exposed until the different gray values of the halftone image motif locally through the different structure thicknesses assigned to this gray value of the expanded raster structures are reproduced.

Which gray value range of the halftone original by which structure thickness depends on the number and height of the steps in the contact grid and the exposure time during the rasterization process and can be controlled in a targeted manner. That The rasterized image motif obtained in this way can then be used for the production of printing plates 25 and used for printing recording media 26.

The advantage of this manufacturing process is that any Complicated structure with simple, photo-technical methods in a contact grid can implement. The halftone reproduction of a screen rasterized with such a contact grid Image motifs by the respective halftone reproducing, thickening or tapering structural elements of the basic grid structure can be precisely adjusted, d. H. the number of stages can be arbitrarily - within the framework of the tech- niches Possibilities - increase so that, if desired, a quasi-continuous one until a continuous gray value or blackening curve can be obtained.

In addition, the halftone reproduction can be achieved through the precise setting move the step heights as desired, so that certain gray levels of the template Bring it into the desired ratio when rasterizing.

A technical aid for both the single-step process as well as for the contact grid method when working with very finely structured Motifs and grids use the enlargement technique.

When a picture motif is rasterized, the picture information occurs all the more The narrower and finer the structure of the grid, the clearer and more precise it is. The more levels you use, the better and more precise the halftones of the image motif become reproduced.

For this purpose it is advantageous for finely structured grids and when working with a large number of stages, i. H. several expanded grid structures, enlarged Grid positives or negatives should be used, since a grid as shown in Fig. 17 without major problems e.g. B. 50 grid negatives or positives of increasing structural strength can be made, if you can with ten, fifteen times or even higher magnification is working. If you enlarge the halftone image to be rasterized, z. B. the mussel on Fig. 12 likewise and shows 50 of these tone value separations increasing Structure strength (i.e. tone value separations, the 50 different gray value areas the halftone original) is obtained with the same process steps as described in the above method an enlarged screened printing template, which is then reduced back to the desired size.

On the other hand, if you use very few steps and you should use the transitions weakened or made a little softer in the grid structures between two levels it is preferable to work with greatly reduced image motifs and grid structures. At the end of the process, the resulting print template will be changed to the desired one Measure enlarged and then shows in the transition areas between the different Structural strengths of the grid or grid widths a continuous course. This As already mentioned above, the effect can be determined by the gradation of the used Explain the line material.

Another method to achieve a better optical preparation The rasterized artwork for printing consists of the one that has already been rasterized Image motif before copying in the basic raster structure or original raster structure to reproduce somewhat blurred on line material in a repro camera and only then copy in the basic grid structure.

The somewhat blurred reproduction also has the effect of the raster gradations to draw softer in the rasterized image motif. This method is also applicable when using a contact grid, if the narrowest step in the contact grid is left out is.

Finally to the photo-technical "contact raster halftone process" it should be mentioned that with this process new ways for the production of classic Contact grids such as dot, line or cross grids open up without having to manufacture the glass engraved grid to be instructed. So can be about common Line grid or produce other grid structures in large numbers and with high quality, if one a multi-level contact grid, d. H. one with several expanded grid structures produced contact grid, on an enlarged scale with a very large number of steps produces, this contact grid is reproduced somewhat blurred, then on the the required size and the desired number of duplicates of this original manufactures. This means you have the option of using the contact grid method to create a Any number of identical grids, which have a quasi-continuous to have a continuous gray value or blackening course and in this exactly can be adjusted in an economical way without going through the production of glass engraved grids to make. With this procedure you can not only change the gradation of a Approve the classic contact grid (see Fig. 23) in steps with any precision and shape it almost continuously with the above-mentioned technical aids, it is even possible to use any desired gray value or blackening profile in the contact raster achieve, so z. B. that shown in Fig. 24, with which a halftone picture motif can be converted into a raster image with a strongly emphasized light-dark contrast.

Two "engineered" variants of the contact grid method are briefly described below outlined.

After one, as with the "engineered" single-step process described above a basic grid structure and expanded grid structures using computer graphics or with the help of the scanning device - with the information about Position and shape of the grid elements for each expanded grid structure separately are recorded - each expanded raster structure is assigned a gray value, that of the stored position and shape information of the corresponding expanded Grid structure is added. H. adds the assigned gray values point by point for each expanded raster structure and saves from this resulting information, one obtains an "electronic contact grid", d. H. a grid structure, the shape of which is stored point by point, with each point a gray or blackening value is assigned. With this information z. B.

the laser beam writer can be controlled by this "electronic Contact grid "exposed or transferred onto an unexposed halftone material, see above that you get a classic photographic contact grid.

However, a direct "electronic" rasterization is also possible, by scanning the halftone original, saving its gray values point by point and using the stored "electronic" contact grid are superimposed in such a way that the Gray values of the electronic contact grid and the halftone original are added and when a defined, empirically determined threshold for resulting information is saved for each point. This resulting Information (they are the "shape information" of the screened image) then the rasterized image motif through different structural strengths of the basic raster structure again, which is displayed on the screen ~ and / or by means of the laser beam recorder Transferred directly to printing plates or first onto an unexposed line material can be.

A slightly modified variant for generating an electronic one Contact grid "consists of creating a grid basic structure, as above, whose Shape is saved. From this basic grid structure one takes a characteristic one Element and defines a gray value or

Gradation of blackening (e.g. by computer graphics, by for various Cross-sections of the characteristic raster element show a blackening or gray value curve is defined; which can also be shown in perspective on the screen, so that a three-dimensional image of the blackening or gray value curve is in a Grid element results). This information generated for a grid element is displayed on transfer the entire basic grid structure, so that one also has an "electronic Contact grid "with which you can continue working as shown above by either electronically rasterized or a photographic contact raster created will.

Finally, let me repeat the essential advantages of the inventive Procedure listed. What all variants have in common is that they can have any structure can be used as a raster and that the conversion of the gray value of the original into a specific structural strength of a basic grid structure in all details is controllable. An advantage of the single step processes, if desired, is one certain "exclusivity" and uniqueness of the grid structures and the rasterization, because such a rasterized image motif without precise knowledge of the production recipe (i.e. degree of expansion of the basic grid structure, exact course of the basic grid structure, Assignment of the expanded raster structure to the gray value area of the one to be rasterized Halftone original etc.) cannot be reproduced can adorn. New opportunities result also for banknote and security printing, since this is the first time to reproduce an image motif using an arbitrarily complex safety line pattern leaves. For example, if centric guilloches are used, the Multi-colored image information through the central area of the security line pattern reproduce and run out in simple guilloche lines without image information permit. The line course of the guilloches would also be uninterrupted by the Track image motif. This integration of image information into the safety line pattern Forgery and imitation attempts are made considerably more difficult.

A special one that is highly interesting in terms of printing and security technology Possibility of printing from the above methods for recording media, in particular securities results, consists in the different, rasterized Transferring gray value areas of the halftone image motif onto two different printing plates (e.g. also by engraving the printing plates directly using the EDP-controlled Laser beam writer or by the techniques outlined above), using a printing plate for printing the front side and the other printing plate: - for printing the back side of the recording medium is used. Part of the image information (an overlay of selected rasterized gray value areas) is then on the front, the other part of the image information (the rest of the overlaid and rasterized Gray value areas) on the back of the recording medium, so that in transmitted light the full screened image information becomes visible. To do this, of course, the for the reverse side certain rasterized Image portion in reversed Form transferred to the printing plate and when printing the recording medium on accurate register printing must be taken into account.

A particular advantage of the phototechnical process is that it can be implemented with relatively simple technical possibilities and still Deliver results that are unthinkable with classic raster technology.

Apart from the great expenditure on equipment in the "engineered" These processes are particularly suitable for creating new types of grid shapes with any Try out the gray value or blackening curve, with all parameters immediately changeable and the effects of this change are visual at the same time can be displayed, so that exclusive grid requests can also be fulfilled, both for the production of contact grids and for the direct electronic Screening, which relates to the production of printing plates or printing templates.

L eerseite

Claims (29)

PATENT CLAIMS 1. Method for rastering halftone image motifs, the different halftones or gray values of the image motif by more or less strong changes in the structural strength of a basic grid structure are shown are indicated by the fact that (a) all or selected gray values of the halftone image motif is one characteristic of the gray value in question, Freely selectable change in the structural strength of the form according to any basic grid structure is assigned, (b) for each gray value selected under (a) the proportions of the halftone image motif, which have this gray value into the change assigned to this gray value the structural strength of the basic grid structure can be implemented by the relevant Portions of the halftone image motif individually or in summarized form the changed Structural strengths of the basic grid structure, which are also individually or combined Form can be overlaid. 2. The method according to claim 1, characterized in that g e k e n n -z e i c h n e t, that (a) the entire gray value curve of the halftone image motif is divided into gray value areas whose limits are freely definable on the gray scale, (b) from one of the Form according to any basic grid structure, gradually expanded grid basic structures are generated, the expansion of the structural strength of the basic grid structure is freely selectable for each expanded grid structure, (c) all or only selected ones under (a) de- defined gray value areas a certain of the below (b) generated, expanded grid structures are assigned, (d) the expanded Grid structures individually, one after the other or together in a summarized form the gray value areas of the halftone image motif assigned to them under (c), which the can also be present individually or in summarized form, are superimposed, and that (e) the portions of the halftone image motif which have a gray value from one of the have gray value areas selected under (c), locally through this gray value area assigned, expanded raster structure are reproduced. 3. The method according to claim 2, characterized in that g e k e n n -z e i c h n e t, that (a) from the basic grid structure expanded grid structures in the form of as Negative or positive film produced line replicas of increasing structural strength which act as black-and-white rasters with a stepped gray value gradient, (b) the same number of tone value separations from the halftone image to be screened as negative or positive film are produced, each of which has a certain gray value range reproduces the halftone image motif, (c) the negative or positive film Line reproduction with the broadest structure thickness of the grid together with the negative or positive film available tonal value extract of the lowest structural strength, which the Reproduces portions of the halftone image motif with the darkest gray values, in contact arrangement is placed on an unexposed line material, (d) this arrangement exposure is continued until in the areas of the line material where the arrangement is completely translucent, a complete blackening has taken place, so that the gray value range of the halftone image motif determined by the tone value extract the grid with the narrowest structure thickness is reproduced, (e) with the line replicas with decreasing structure strength the tonal value extracts with increasing Proceed in the same way as the structure thickness and each new unexposed line material becomes, (f) the line materials present as positive or negative film, from each of which has a different gray value range of the halftone image motif reproduces a different structural strength of the basic grid structure, for production a screened overall image motif can be used. 4. The method according to claim 2, characterized in that g e k e n nz e i c h n e tr that (a) from the basic grid structure expanded grid structures in the form of as Negative or positive film produced line replicas of increasing structural strength which act as black-and-white rasters with a stepped gray value gradient, (b) the line reproduction available as negative or positive film with the lowest Structural weakness together with a negative or positive film of the one to be rasterized Halftone image motifs placed in contact arrangement on an unexposed line material is, (c) this arrangement is exposed until in the areas of the line material, where the arrangement lets through enough light to blacken the coating material to cause a reproduction of a certain gray value range of the rasterized Half- tone image motif takes place through the narrowest grid structure, (d) with the line reproduction of the next larger structure thickness and a new unexposed one The same method is used for the coating material, the exposure time being increased in such a way that that a correspondingly larger gray value range of the halftone image motif in this stronger Structure is implemented, (e) using this procedure for each additional line copy with increasing structural strength is carried out analogously, (f) as a positive or negative film existing line materials, each of which has a different gray value range of the halftone image motif due to a different structural strength of the basic grid structure reproduces, are used to produce a screened overall image motif. 5. The method according to claim 3 or 4, characterized in that g e -k e n n z e i c It should be noted that the number of line replicas increases with the thickness of the structure is that a continuous gray value conversion of the halftone image motif in continuous increasing structural strengths of the basic grid structure results. 6. The method according to claim 3 or 4, characterized in that g e -k e n n z e i c h n e t that the assignment of the gray value area to the raster structure thickness takes place in such a way that that the gray value areas of the halftone image motif in non-proportional widening the structural strength of the basic grid structure are implemented, so that the rasterized Image motif has a gray value shift compared to the halftone image motif. 7. The method according to claim 2, characterized in that g e k e n n -z e i c h n e t, that (a) from the basic grid structure expanded grid structures in the form of as Negative or positive film produced line replicas of increasing structural strength which act as black-and-white rasters with a stepped gray value gradient, (b) each of these line replicas individually in contact arrangement on a suitable unexposed one Halftone material is placed and exposed for a certain period of time, so that one as an end result a positive or. Negative contact counselor receives which one through the basic structure grid and the exposure times are determined and precisely adjustable Has the course of blackening of the grid profile, (c) this positive or negative contact grid is used to produce a screened overall image motif. 8. The method according to any one of claims 3 - 7, characterized g e k e n n z e i n e t that the line replicas of increasing structural strength on photographic Paths created by targeted over-exposure of a new line material will. 9. The method according to any one of claims 3 - 7, characterized g e k e n n z e i c h n e t that the basic grid structure and the expanded grid structures generated by means of computer graphic techniques and by means of a controlled laser beam writer can be transferred to a new line material each time. 10. The method according to claim 3, characterized in that g e k e n nz e i c h n e t, that the tone value extracts are produced by photographic means. 11. The method according to claim 3, characterized in that g e k e n nz e i c h n e t, that the tone value extracts obtained via a scanning device and by means of a controlled laser beam writer on a new line material each time will. 12. The method according to any one of claims 3 - 7, characterized g e k e n n shows that after the halftone image motif has been rasterized, the basic raster structure is copied into the image in register. 13. The method according to any one of claims 3 - 12, characterized g e k e n n shows that the individual steps of the process are compared to the original either enlarged or reduced basic structures, line replicas or halftone image motifs be performed. 14. Use of the rasterized parts of the motif according to the Method according to one of Claims 1 to 13 for the production of printing templates, printing plates or recording media printed with the image motif. 15. The method according to claim 1, characterized in that g e k e n nz e i c h n e t, that (a) the basic grid structure and the expanded grid structures by means of computer graphics Techniques or generated by scanning photographic or graphic templates (b) the position and shape of the grid elements for the grid basic structure and the expanded raster structures are saved separately, (c) the gray value range of the halftone image motif divided into gray value areas and the halftone image motif in this way is scanned that the parts of the semitone picture motifs, which one Have gray value from one of these areas, separately for each gray value area are stored, (d) all or only selected gray value areas in each case be assigned to a widened grid structure thickness, (e) for each gray value area separately the information with expanded raster structure and assigned gray value portion of the halftone image motif are superimposed point by point so that a resulting Information is formed and stored that provides information on whether this Dot raster structure and image portion is present, so that every gray value portion of the image motif is represented by the associated grid structure, (f) this information via the individual screened gray value components of the halftone image motif for production a screened image motif can be used. 16. The method according to claim 15, characterized in g e k e n nz e i c h n e t, that with the information about the screened gray value components of the halftone image motif a laser beam writer is controlled separately for each gray value range the screened gray value components are exposed on separate film layers or transfers directly to printing plates. 17. The method according to claim 15, characterized in that g e k e n nz e i c h n e t, that the different screened gray value components are first superimposed and then on a layer of film can be exposed or transferred to a printing plate. 18. The method according to claim 1, characterized in that g e k e n n - z e i c h e t that (a) the basic grid structure and the expanded grid structures by means of computer graphic techniques or by scanning photographic or graphic templates are generated, (b) the position and shape of the grid elements of the Basic grid structure and the expanded grid structures are saved separately, (c) each expanded raster structure is assigned a gray value and the information is added about the position and shape of the expanded grid structure, (d) this information are superimposed over the expanded raster structures in such a way that the gray values are added point by point, so that each point of the resulting grid structure a gray value is assigned and this information is stored so that an "electronic contact grid" results, (e) a halftone original scanned in this way is that the gray value is stored for each point, (f) the information about the gray values of the halftone image motif with the information of the "electronic contact screen are superimposed in such a way that for each point of this superimposed arrangement the Gray values are added and when a threshold value is exceeded for this point positive information is stored, so that this resulting information reproduce the rasterized image motif. 19. The method according to claim 1, characterized in that it is e k e n n -z e i c h n e t that (a) using computer graphic techniques or scanning of photographic or graphic templates are generated on a basic grid structure, (b) The position and shape of the grid elements of the grid basic structure is stored, (c) by means of computer graphic techniques for one or more cross sections of a characteristic A grayscale value or blackening curve is defined and saved, (d) this gray value curve is transferred to the entire basic raster structure and saved so that an electronic contact screen "is obtained, (e) then a halftone original is scanned in such a way that the gray value is stored for each point, and the Information about the gray values of the halftone image motif with the information of the "Electronic contact grid" are superimposed in such a way that for each point this superimposed arrangement the gray values are added and when one is exceeded Threshold value for this point positive information is stored, so that this resulting information reproduce the rasterized image motif. 20. The method according to any one of claims 18 or 19, characterized g e k e n n z e i n e t that with the stored information about the rasterized Halftone image motif a laser beam writer is controlled, which this on a film layer, a photo paper, a printing plate or a carrier material transfers. 21. A method for producing a film contact grid, characterized in that g It is not noted that (a) raster structures expanded from a basic raster structure in the form of line replicas available as negative or positive film is increasing Structural strength can be produced, which as a black and white grid with stepped Gray value run, (b) each of these line replicas individually placed in contact arrangement on a suitable unexposed halftone material and a certain period of time is exposed, so that the end result is a positive or. Negative contact grid, which one through the basic structure grid and the Exposure times determined and precisely adjustable blackening progression of the grid profile having. 22. A method for producing a film contact grid, thereby g It is not noted that (a) a basic grid structure and the expanded Raster structures using computer graphic techniques or by scanning photographic images or graphic templates are generated, (b) the position and shape of the grid elements the basic grid structure and the expanded grid structures are saved separately (c) each expanded raster structure is assigned a gray value and the information is added about the position and shape of the expanded grid structure, (d) this information are superimposed over the expanded raster structures in such a way that the gray values are added point by point, so that each point of the resulting grid structure a gray value is assigned and this information is stored so that results in an "electronic contact grid, and (e) with this information a laser beam writer is controlled, which transfers the electronic contact grid "to a halftone material. 23. A method for producing a film contact grid thereby g e it is not indicated that (a) by means of computer graphic techniques or Scanning A basic grid structure is generated from photographic or graphic templates, (b) the position and shape of the grid elements of the grid basic structure is saved, (c) using computer graphic techniques for one or more cross-sections of a characteristic A grayscale value or blackening curve is defined and saved, (d) this gray value curve is transferred to the entire basic raster structure and saved so that a 1 "electronic contact grid" is obtained (e) with this information a laser beam writer is controlled by this electronic contact grid transfers to a halftone material. 24. Screened image motif in which a halftone image motif through local Expansions of a basic grid structure is shown, thereby g e k e n nz e i n e t that the basic grid structure is a complicated security line pattern is, which has entanglements and multiple crossings. 25. Image according to claim 24, characterized in that that the line pattern is a guilloche pattern, the mesh size a being that at line crossings resulting meshes and the line width b are coordinated so that the line width b is always smaller than half the width of the machine a. 26. Image according to claim 25, characterized in that that even in the darkest parts of the picture there are no lines or There is blotchiness so that every single line is recognizable and in its course is trackable. 27. Image according to any one of claims 24-26, characterized in that it is not It is not indicated that the present as printing ink on a carrier material Lines of the security line pattern consist of different layers of paint, so that there is a stepped pyramid-like cross-section. 28. Image according to claim 27, characterized in that that one or more colored layers of metallic, metameric, thermochromic or photochromic colors. 29. Image motif according to claim 24-26, characterized in that g e -k e n n n z e i c h n e t that the basic grid structure is congruent on both sides of a translucent Carrier material is arranged, the degree of expansion of the basic grid structure is different on both sides, so that the complete rasterized image motif only appears in transmitted light.